1. Field of the Invention
The present invention relates to an apparatus and method for collecting and thereafter recycling the initially cold portion of a household hot water stream that is usually wasted, and more particularly to a temperature sensing water flow diversion circuit that directs the initially cold part of the hot water flow into an accumulator for subsequent cold water use.
2. Description of the Prior Art
With increasing population density prudence in the use of the world's resources has become a dominant concern. One resource that is central to all the functions of life is potable water, a resource that is growing scarce and is therefore now the primary concern of most municipalities. Simply, the availability of fresh water now limits most municipal growth and virtually all housing expansions are currently associated with costly water recycling or conservation measures, a cost exchange that will only continue to rise in a world that increases in its mean temperature.
For a long time it has been recognized that one substantial component of unnecessary water waste is the early, cool part of a hot water stream that is currently just dumped down the drain until the desired stream temperature is reached. In multiple dwelling structures these losses can become quite large and the economies of scale have led to the use of continuously circulating hot water loops which shorten substantially the length, and therefore the volume, of the branch circuits feeding each hot water valve. While these continuously circulating arrangements have obtained substantial savings in water use, the sheer number of the various circuits that branch off from the loop results in significant waste of fresh water nonetheless.
In the past various mechanisms have been proposed that in one way or another divert the initial part of the hot water stream into an accumulator or other storage cavity to be saved and thereafter drained with the cold water flow as cold water is demanded. While suitable for the purposes intended most of the prior mechanisms fail to fully address the volumetric requirements of such storage, i.e., the physical size and cost of the storage reservoir itself, and also its distribution throughout a household and therefore the necessary household space burden devoted thereto.
Those skilled in the art, of course, will appreciate that an exactly paired hot water—cold water demand sequence is rare in a household, just like exactly sequenced heads—tails pairings in any statistical process, and a typical residential bathroom will therefore need to accommodate several hot water demand initiation sequences in its reservoir sizing. Simply, any practical implementation will need a volumetric storage capacity surplus that will accommodate several hot water—hot water sequences in a row in order to be useful since a full storage reservoir cannot provide the needed diversion volume at all. In a busy household where the sequential morning hot water demands often exceed the water heater capacity, and little or no cold water is added to cool the stream, a practically sized accumulator needs to accommodate several hot water demands each of a volume equal to the volume of the utilized plumbing branch.
Moreover, to optimize the reservoir volume one must also consider the efficacy of the reservoir draining process itself, a process effected when cold water is demanded since the same statistical processes operate also on the cold water side. To obtain full benefit this draining rate should be maximized, i.e., should be at the full cold water flow demanded, thus limiting the usefulness of any drainage mechanism in which the draining flow is entrained with, and/or carried along by, the primary cold water flow. Simply, to assure maximal reservoir drainage rates and thus improve any statistical bias the drained volume in each of the cold water incidents needs to be maximized.
The foregoing volumetric concerns are not the whole of it. Like in any statistical process the probabilities of long sequences of uninterrupted repeating hot water demands are sufficiently significant that even a very large reservoir sizing will be quickly exceeded. To accommodate these real possibilities the water conserving system will either need to include very large and therefore costly reservoirs or must automatically revert to a by-passing state in order to retain the original basic water supply functions.
While these several concerns have perhaps had individual attention in the prior art, the complete combination of all these notions has not been fully accommodated. For example U.S. Pat. No. 4,697,614 to Powers et al., while teaching a diversion into the accumulator of the initial hot water stream, does so by a manually effected selector. The collected water in the accumulator is thereafter drained by entrainment with a reduced pressure cold water flow. While suitable for the purposes intended this particular arrangement demands manual attention to effect its use while also protracting the accumulator drainage by the reduced flow therefrom.
By further example U.S. Pat. Nos. 5,339,859 and 5,452,740, both issued to Bowman, while each replacing the manual selector with a temperature sensing flow control in the hot water circuit, similarly fail to optimize the draining part of the process, with the '740 patent resolving the drainage paradox by directing the accumulated water to irrigate plants. While once more each of these references, and the many others, achieve their respectively intended purposes, the central concern of a convenient, fully automated conservation arrangement has not been fully addressed.
Thus the full hot and cold water use dynamics of a typical household are neither fully appreciated nor attended at all in the prior art and because of the complex interplay of these several functions the well appreciated benefits of water conservation have not been fully realized. An automated system that fully accommodates these several competing functions in a manner that is virtually imperceptible to the user is therefore extensively desired and it is one such system that is disclosed herein.